1+ • Peterbaylissite Hg3 (CO3)(OH) 2H2O c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Orthorhombic, pseudotetragonal. Point Group: 2/m 2/m 2/m. Euhedral to subhedral crystals, to 0.2 mm, elongated parallel [001], wedgelike, may be platy; isolated and in clusters. Physical Properties: Fracture: Irregular. Tenacity: Brittle. Hardness = < 5 D(meas.) = n.d. D(calc.) = 7.14 Optical Properties: Opaque. Color: Black to dark red-brown; in polished section, gray with slight blue tinge. Streak: Dark brownish black. Luster: Submetallic to adamantine. Optical Class: Biaxial. Anisotropism: Weak, dark gray to brown. Bireflectance: Weak to moderate. R1–R2: (400) 12.0–13.2, (420) 11.8–12.8, (440) 11.6–12.6, (460) 11.5–12.3, (480) 11.3–12.1, (500) 11.2–11.9, (520) 11.1–11.7, (540) 11.0–11.6, (560) 10.9–11.5, (580) 10.9–11.5, (600) 10.8–11.4, (620) 10.7–11.3, (640) 10.8–11.2, (660) 10.6–11.2, (680) 10.6–11.2, (700) 10.6–11.2 Cell Data: Space Group: P cab. a = 11.130(2) b = 11.139(3) c = 10.725(3) Z = 8 X-ray Powder Pattern: Clear Creek claim, California, USA. 2.648 (100), 2.969 (70), 2.786 (70), 2.419 (60), 4.84 (50), 6.35 (40), 4.95 (40) Chemistry: (1) (2) CO2 n.d. 6.16 Hg2O 87.4 87.54 H2O n.d. 6.30 Total 100.00 (1) Clear Creek claim, California, USA; by electron microprobe, average of two analyses; 2− 1− (CO3) , (OH) , H2O, confirmed by IR, the chemical formula determined by crystal-structure • analysis. (2) Hg3(CO3)(OH) 2H2O. Polymorphism & Series: Dimorphous with clearcreekite. Occurrence: Very rare in a mercury deposit in silicate–carbonate rock, hydrothermally altered from serpentinite, probably formed as an alteration product of cinnabar. Association: Ferroan magnesiochromite, ferroan magnesite, cinnabar, metacinnabar, mercury, quartz. Distribution: From near the Clear Creek mercury mine, New Idria district, San Benito Co., California, USA. Name: Honoring Dr. Peter Bayliss (1936– ), Professor of Mineralogy, University of Calgary, Calgary, Canada, for his many contributions to mineralogy. Type Material: The Natural History Museum, London, England, 1993,431 and E.1492; Canadian Geological Survey, Ottawa, Canada, 67533. References: (1) Roberts, A.C., T.S. Ercit, L.A. Groat, A.J. Criddle, R.C. Erd, and R.S. 1+ • Williams (1995) Peterbaylissite, Hg3 (CO3)(OH) 2H2O, a new mineral species from the Clear Creek claim, San Benito Co., California. Can. Mineral., 33, 47–53. (2) (1995) Amer. Mineral., 80, 1074–1075 (abs. ref. 1). All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission of Mineral Data Publishing..